There is known the car steering wheel electromechanical booster, comprising a steering wheel torque sensor, a car speed sensor, a control unit, connected to said sensors as well as an electric motor, which is controllable in response to signals from the control unit and which connected to an output shaft by means of speed reduction device (see the RU 2158692, Int. CL: B 62 D 5/04, 2000).
The electric motor in this device is a three-phase machine with a number of teeth on stator equal to 12, and on rotor, equal to 8, but a magnetic system of the electric motor is made with a relative slanting of rotor and stator teeth, therewith, a the crown slanting and width of the stator and rotor teeth with respect to an air gap are selected in determined correlations to a tooth pitch with respect to the rotor.
The known device drawbacks are as follows:
                an electromagnetic torque pulsation on a shaft;        large dimensions and weight;        the speed reduction device presence in the steering wheel booster, which complicates the construction;        the weight and dimensions values are increased ones;                    a car driving safety is impaired due to a possibility of steering wheel self-locking upon the steering wheel booster failure occurrence.                        
The closest analogue with respect to the declared steering wheel electromechanical booster is a steering wheel electromechanical booster, comprising a body, wherein there are positioned input and output shafts, which are interconnected with the aid of a torsion bar, which is embodied in the form of a torque sensor sensing element, and are linked with the steering wheel and a steering mechanism by the other end thereof, an electric motor, comprising a stator with a magnet core, having n pronounced poles, and with a three-phase winding, which is accomplishes with coils, that are placed in six equal alternating phase areas in such a way that one area is assigned to one pole and with several coils belonging to one phase in each phase area, and a rotor with n−2 poles, which are embodied in the form of permanent magnets, therewith, the rotor is mounted on the output shaft, a controllable source for supplying the stator three-phase winding of the electric motor, a sensor of the rotor position of the electric motor and a control unit, inputs of which are connected to the outputs of the torque sensor and the electric motor rotor position sensor, but the output of which is connected to the control input of said supplying source. (RU 2181091, Int. CL: B 62 D 5/04, 2002).
In the known device the coils of the electric motor stator three-phase winding in the phase areas, belonging to one phase, are connected in a series aiding configuration.
The known device drawbacks are as follows:                a weak internal damping due to the absence of shock damper contours on the rotor and on the stator of the electric motor. It leads to a disturbance torque transfer onto the steering wheel upon an acute exposure to wheels on the part of roadway;        a poor technological effectiveness of the electric motor stator manufacturing and the ins and the outs of an optimal mechanical characteristic obtainment.        
The given drawbacks are conditioned in that upon low frequencies of supplying and upon low voltages the stator winding of the electric motor has a small number of phase coil turns and a large cross-section. It aggravates its laying into slot openings.
An electrical motor for a high-torque direct-drive electromechanical booster of steering wheel should have a maximal moment upon the given dimensions with maximal electromagnetic loads.
Upon the given dimensions of the electrical motor and upon the given magnetic induction a form of mechanical characteristic (i.e., points of nonworking stroke and short circuit) is determined by means of number of phase turns.
Upon a small number of phase turns, connected in series (it occurs in the known electrical booster of the steering wheel), the ins and the outs arise in an obtainment of the optimal mechanical characteristic due to a large discretisation of varying of the number of turns upon their selection.